The present invention relates to an encasement for shielding electromagnetic radiation for a battery cell and for a battery system and to a process for producing said encasement. The invention further relates to a battery cell and to a battery system.
It is apparent that, in the future, new battery systems having very high demands placed on them in terms of reliability, safety, performance and lifetime will be employed not only in stationary applications, such as wind power plants, and in hybrid or electric motor vehicles but also in electronic equipment, such as laptops or mobile telephones.
So-called lithium-ion battery cells in particular are used here. Said cells are notable for, inter alia, high energy densities, thermal stability and very low self-discharging. Lithium-ion battery cells comprise a positive electrode and a negative electrode at which lithium ions can be reversibly inserted and deinserted during charging and discharging. This is also known as intercalation and deintercalation.
A battery cell generally comprises one or more electrode units in the form of a roll. An electrode unit comprises two collector foils which, with a separator placed between them, are wound into a battery roll. The collector foils of the electrode units are electrically connected in known fashion to the poles of the battery cell which are also known as terminals.
A battery cell further comprises a metallic housing, made of aluminum for example. The housing is generally prismatic or cuboid shaped and pressure-resistant. Once the electrode units have been connected to the terminals the housing is filled with an electrolyte solution.
Lithium-ion battery cells are relatively sensitive to environmental influences, particularly to air and moisture. The abovementioned housing offers protection against said environmental influences.
A plurality of such battery cells may be combined to form a battery system also known as a battery pack.
Battery cells need to meet electromagnetic compatibility requirements. This means that the battery cell must not be affected by external electromagnetic fields and the battery cell itself must not emit electromagnetic fields that cause other equipment in the vicinity to be affected.
EP 1 403 942 A1 discloses lithium-ion battery cells of a battery system which are provided with an encasement made of polypropylene, polyethylene terephthalate, polycarbonate or a composite material formed therefrom. To shield electromagnetic radiation the encasement is provided with a coating comprising nickel powder or carbonyl iron powder dispersed in high density in acrylic prepolymer.
EP 2 072 309 A1 discloses a battery unit for use in an electric vehicle. To shield electromagnetic radiation the vehicle is provided with a frame structure with metal members which peripherally surround the battery unit. For shielding purposes the vehicle may further be provided with an insert member comprising metal embedded in a plastics resin.
EP 2 465 719 A1 discloses a battery housing for receiving a plurality of battery modules for operating an electric vehicle. The battery housing comprises tray members comprising metal sheets for shielding electromagnetic radiation.